Question
If I plant a row of Thujas against a fence, approx 4 feet from the fence and four feet between each other, will the Thujas eventually push down the fence?  I have read the width can be from 5 feet all the way to 20??  Can i prune the the fence side of the trees to keep them away from it?  If I do this, will it stunt the growth of the tree?  I don't want to plant the tree to far from the fence and loose room in my yard.  But, do want them to grow tall enough to create a privacy/wind block.

Answer
No planting them 4 feet from the fence will not cause them to push the fence over. When they get larger their limbs will rub the fence. At that time all you need to do is prune the limbs back on that side of the tree. This will not effect the growth of the tree. For a privacy/ wind break you have planted them correctly.